Police have long relied on dogs to uncover illegal drugs, negotiate disaster areas, and find fugitives on the run.More recently, law enforcement officials have started to use canine scent lineups where dogs choose a suspect’s smell out of a group of people.

The dogs are given the target scent from items found at the crime scene and then walked by a lineup of containers that contain scent swabs from a group of people including the suspect.The dog identifies a scent match through a trained signal, often a bark.

In 2004, the F.B.I published a report saying that the use of scent dogs was a proven tool that could establish connection to a crime, but should not be used as primary evidence.

Many states, including Alaska, Florida, New York and Texas, currently use scent lineups, but the technique has been problematic, leading some courts to reject scent lineup evidence.There is no doubt that dogs can accurately identify a match, but critics say that the possibility of cross-contamination is too great.

The most famous scent dog handler, Deputy Keith A. Pikett of the Fort Bend County Texas Sherrif’s Department, has performed thousands of scent lineups since the 1990s.Pikett fell into field when he and his wife trained their Bloodhound, Samantha, to follow scents for fun.They started volunteering to search for lost children, added more Bloodhounds, and soon their services grew into an unintentional career.

Recently, some of the people Pikett helped convict have been cleared through DNA, resulting in a number of lawsuits.The Innocence Project estimates that 15-20 people are in prison based solely on Pikett’s scent lineups, even when it conflicted with other information.

I hate to see a potentially valuable tool be dismissed because it wasn’t used properly.I think that with the right protocol and standard procedures, scent lineups could find their place in law enforcement.